592 resultados para OVERGROWN GAN
Resumo:
An outbreak of foot rot occurred in the ibex colony "Vanil Noir" in Switzerland from May to December 2014. This article describes field observations and the analyses carried out on the limbs of 3 animals submitted for postmortem examination. Disease signs observed in the field included lameness, poor body condition and overgrown hooves. Macroscopic examination of selected limbs revealed severe lesions in all of them, including interdigital inflammation with ulceration and malodorous exudation. Histological changes were consistent with chronic laminitis with bone resorption, which was not detected at radiographical examination. Grocott-positive organisms compatible with Dichelobacternodosus were detected in the lesions. Samples collected from the lesions were positive by polymerase chain reaction for benign D. nodosus, which is typically associated with only mild lesions in domestic sheep. Whether D. nodosus is endemic in the colony or had previously been transmitted from sympatric domestic livestock is unclear. The unusual warm and humid weather conditions in 2014 may well have contributed to the outbreak.
Resumo:
Ocean Drilling Program Hole 923A, located on the western flank of the Mid-Atlantic Ridge south of the Kane Fracture Zone, recovered primitive gabbros that have mineral trace element compositions inconsistent with growth from a single parental melt. Plagioclase crystals commonly show embayed anorthitic cores overgrown by more albitic rims. Ion probe analyses of plagioclase cores and rims show consistent differences in trace element ratios, indicating variation in the trace element characteristics of their respective parental melts. This requires the existence of at least two distinct melt compositions within the crust during the generation of these gabbros. Melt compositions calculated to be parental to plagioclase cores are depleted in light rare earth elements, but enriched in yttrium, compared to basalts from this region of the Mid-Atlantic Ridge, which are normal mid-ocean ridge basalt (N-MORB). Clinopyroxene trace element compositions are similar to those predicted to be in equilibrium with N-MORB. However, primitive clinopyroxene crystals are much more magnesian than those produced in one-atmosphere experiments on N-MORB, suggesting that the major element composition of the melt was unlike N-MORB. These data require that the diverse array of melt compositions generated within the mantle beneath mid-ocean ridges are not always fully homogenised during melt extraction from the mantle and that the final stage of mixing can occur efficiently within crustal magma chambers. This has implications for the process of melt extraction from the mantle and the liquid line of descent of MORB
Resumo:
A detailed record of the strontium-87 to strontium-86 ratio in seawater during the last 100 million years was determined by measuring this ratio in 137 well-preserved and well-dated fossil foraminifera samples. Sample preservation was evaluated from scanning electron microscopy studies, measured strontium-calcium ratios, and pore water strontium isotope ratios. The evolution of the strontium isotopic ratio in seawater offers a means to evaluate long-term changes in the global strontium isotope mass balance. Results show that the marine strontium isotope composition can be used for correlating and dating well-preserved authigenic marine sediments throughout much of the Cenozoic to a precision of +/- 1 million years. The strontium-87 to strontium-86 ratio in seawater increased sharply across the Cretaceous/Tertiary boundary, but this feature is not readily explained as strontium input from a bolide impact on land.
Resumo:
The D/H, 18O/16O and 87Sr/86Sr ratios of the basaltic basement from the Leg 83 section of DSDP Hole 504B show that in that area the oceanic crust has experienced intensive but not pervasive alteration. Isotope ratios of the basalts are very heterogeneous because of an input of oxygen, hydrogen, and strontium from seawater. The hydrogen isotopic composition of many samples displays the complete thermal history of the water-rock interactions. High-temperature mineral formations (actinolites, epidotes, and chlorites) were overgrown by a mineralization at lower temperatures (mixedlayer smectites, iddingsites, and smectites) during successive stages of cooling of the oceanic crust by cold seawater. From 87Sr/86Sr data bulk water/rock ratios up to 5:1 have been calculated. There is evidence that some primary minerals like high-An plagioclases contain oxygen from altered basalts. We have discussed the probability that there existed a seawater/crust interface, now at a depth of 620 m sub-basement, during the high-temperature water/rock interactions. This interface was covered during later magmatism by thick flows, pillow lavas, and intrusives.
Resumo:
La recuperación de la democracia en diciembre de 1983, fue el inicio de una nueva etapa en la vida de la República Argentina. Sin embargo, ciclos repetidos de ilusiones y desilusiones, de incertidumbres y esperanzas, de encuentros y desencuentros, de proyectos y frustraciones, marcaron fuertemente a toda la población y a las instituciones que la representan. La educación, las escuelas y sus protagonistas no quedaron fuera de esta realidad, lo que limitó su posibilidad de mejorar la oferta educativa. Sin embargo, las fuertes experiencias cotidianas, marcaron a cada uno y a las relaciones con el otro, con los otros, con las organizaciones sociales. Se ganó algo muy importante: La vida en democracia. Pero se trastocaron valores y muchos principios éticos quedaron fuertemente mancillados. Esta es la reflexión que nos proponemos.
Resumo:
Ocean Drilling Program (ODP) Leg 114 recovered nannofossil-bearing sediments from seven sites in the high latitudes of the South Atlantic Ocean. Cretaceous sections were recovered from Sites 698 and 700, located on the Northeast Georgia Rise and its lower flanks, respectively. These contain distinctive high-latitude nannofossil floras similar to those from high-latitude areas of the Northern Hemisphere. Most of the biostratigraphic datums used to date the upper Campanian to Maestrichtian interval appear to lie at approximately the same level in both hemispheres. The FAD of Nephrolithus frequens is confirmed to be diachronous with an earlier occurrence in high latitudes. The LAD of Monomarginatus primus n. sp. also appears to be diachronous with a later LAD in the high latitudes of the Southern Hemisphere. Fossiliferous Paleocene to lowermost Miocene sediments were recovered at all seven sites, from the Northeast Georgia Rise in the west to the Meteor Rise in the east. These nannofossil floras, although restricted in diversity and only poorly preserved, are sufficiently distinctive to allow the recognition of 19 zones and three subzones, which are used to date and correlate the cores recovered. Only Site 704 on the Meteor Rise yielded a substantial section of Miocene to Quaternary nannofossil-rich sediments. The nannofossil floras of this section are of very low diversity, with usually fewer than eight species present. Some stratigraphic ranges of important biostratigraphic datum species are observed to be different in the high-latitude sections from those recorded from low-latitude areas. The LAD of Reticulofenestra bisecta, when calibrated by magnetostratigraphy, appears to occur earlier in Hole 699A (within Chron C6CR) than in Hole 703A and possibly Hole 704B and in other published accounts of lower latitude sites in the South Atlantic. The FAD of Nannotetrina fulgens/N. cristata appears to occur later in Hole 702B (Chron C20R) than it does in other published accounts of lower latitude sites in the South Atlantic. Diachroneity is also suspected in the stratigraphic ranges of Chiasmolithus solitus and Chiasmolithus oamaruensis, although poor magnetostratigraphic results through the critical interval prevent confirmation of this. Differences in the relative stratigraphic ranges of lsthmolithus recurvus and Cribrocentrum coenurumlC. reticulatum at Sites 699 and 703 are noted. These possibly suggest warmer surface waters on the eastern side (Site 703) of the middle to late Eocene South Atlantic than those on the western side (Site 699). The diversities of the nannofossil floras and the presence of the warm-water genera Discoaster, Sphenolithus, Helicosphaera, and Amaurolithus reflect the changing surface water temperatures throughout the Cenozoic. Warmer periods are inferred for the late Paleocene to early middle Eocene, late middle Eocene to late Eocene, latest Oligocene to earliest Miocene, and possibly the Pliocene. Colder periods are inferred for the middle Eocene, most of the Oligocene, and the Miocene. Dramatic changes in the nannofossil floras of the Pleistocene of Site 704 are thought to reflect a rapidly changing environment. Monomarginatus primus, a new species from the Upper Cretaceous strata of Hole 700B, is described.
Resumo:
A partir de recientes trabajos de campo dedicados a entender la relación entre las comunidades indígenas y las instituciones del Estado en Brasil y Bolivia, se intenta examinar con mayor profundidad los modos de operación, la reproducción y, en especial, la legitimación de la llamada colonialidad del poder - categoría de los estudios poscoloniales/descoloniales presentada por el sociólogo peruano Aníbal Quijano que ganó proyección dando énfasis justamente a la continuación de los patrones coloniales en la toma de decisiones, después del cierre del proceso histórico y formal del colonialismo político. Entre los distintos puntosanalizados, uno de los cuales emergen con mayor énfasis en la comprensión de la colonialidad del poder es el que oculta detrás de la idea de nación, el fundamento de los proyectos políticos que apoyan al Estado en diferentes contextos. Se entiende, por lo tanto, que sin una profunda deconstrucción (histórica, epistemológica y ontológica) de la nación, que se construyó de acuerdo a la forma establecida por el colonialismo interno y sus vínculos con el sistema-mundo occidental y capitalista dominante, los debates en torno del Estado, en las antiguas colonias europeas hoy "emancipadas" en América Latina, tienden a limitarse a los aspectos superficiales, sin tocar la lógica colonial de exclusión. Hay, todavía, experiencias protagonizadas por los pueblos indígenas de ambos países hacia la construcción de otros paradigmas de políticas públicas
Resumo:
Con el golpe de Estado de Onganía en 1966 comenzó un intento de consolidación de un Estado Burocrático Autoritario. El gobierno de facto, cuya base social era el gran capital, impulsó reformas estructurales en la economía y las instituciones tendientes a la despolitización y la concentración del capital. Este proyecto entró en una crisis irreversible en mayo de 1969 con los hechos de masas conocidos como Rosariazo y Cordobazo. La descomposición de la dictadura llegó a su punto crítico tras el Tucumanazo y el Viborazo. Tras estos hechos Lanusse dio un golpe de Estado, promovió el GAN y la convocatoria a elecciones sin proscripciones para 1973. Se considera que a partir de 1969 se inauguró una nueva etapa en las luchas sociales en Argentina expresada en una ?nueva izquierda?, de agrupaciones revolucionarias armadas, un auge del activismo obrero y estudiantil, etc. Sin embargo, a pesar de que siempre se menciona el rol de los estudiantes del litoral y del interior en el proceso que derrotó a la dictadura, se haya ausente un estudio sistemático de las luchas del movimiento estudiantil de las regiones donde se desarrollaron los mayores enfrentamientos al régimen militar. Aquí presento algunas dimensiones para su investigación
Resumo:
A partir de recientes trabajos de campo dedicados a entender la relación entre las comunidades indígenas y las instituciones del Estado en Brasil y Bolivia, se intenta examinar con mayor profundidad los modos de operación, la reproducción y, en especial, la legitimación de la llamada colonialidad del poder - categoría de los estudios poscoloniales/descoloniales presentada por el sociólogo peruano Aníbal Quijano que ganó proyección dando énfasis justamente a la continuación de los patrones coloniales en la toma de decisiones, después del cierre del proceso histórico y formal del colonialismo político. Entre los distintos puntosanalizados, uno de los cuales emergen con mayor énfasis en la comprensión de la colonialidad del poder es el que oculta detrás de la idea de nación, el fundamento de los proyectos políticos que apoyan al Estado en diferentes contextos. Se entiende, por lo tanto, que sin una profunda deconstrucción (histórica, epistemológica y ontológica) de la nación, que se construyó de acuerdo a la forma establecida por el colonialismo interno y sus vínculos con el sistema-mundo occidental y capitalista dominante, los debates en torno del Estado, en las antiguas colonias europeas hoy "emancipadas" en América Latina, tienden a limitarse a los aspectos superficiales, sin tocar la lógica colonial de exclusión. Hay, todavía, experiencias protagonizadas por los pueblos indígenas de ambos países hacia la construcción de otros paradigmas de políticas públicas
Resumo:
A partir de recientes trabajos de campo dedicados a entender la relación entre las comunidades indígenas y las instituciones del Estado en Brasil y Bolivia, se intenta examinar con mayor profundidad los modos de operación, la reproducción y, en especial, la legitimación de la llamada colonialidad del poder - categoría de los estudios poscoloniales/descoloniales presentada por el sociólogo peruano Aníbal Quijano que ganó proyección dando énfasis justamente a la continuación de los patrones coloniales en la toma de decisiones, después del cierre del proceso histórico y formal del colonialismo político. Entre los distintos puntosanalizados, uno de los cuales emergen con mayor énfasis en la comprensión de la colonialidad del poder es el que oculta detrás de la idea de nación, el fundamento de los proyectos políticos que apoyan al Estado en diferentes contextos. Se entiende, por lo tanto, que sin una profunda deconstrucción (histórica, epistemológica y ontológica) de la nación, que se construyó de acuerdo a la forma establecida por el colonialismo interno y sus vínculos con el sistema-mundo occidental y capitalista dominante, los debates en torno del Estado, en las antiguas colonias europeas hoy "emancipadas" en América Latina, tienden a limitarse a los aspectos superficiales, sin tocar la lógica colonial de exclusión. Hay, todavía, experiencias protagonizadas por los pueblos indígenas de ambos países hacia la construcción de otros paradigmas de políticas públicas
Resumo:
Bright red "jasperoids" were recovered at three positions during Leg 193 drilling below Roman Ruins (Site 1189) in the PACMANUS hydrothermal field. These do not represent fossil exhalative oxide deposits equivalent to those associated with sulfide chimneys at the Roman Ruins seafloor. Rather, they constitute an integral, relatively early stage involving oxidized fluids in the development of veins and breccias that characterize the mostly sulfidic stockwork zone intersected below Roman Ruins in Hole 1189B. They formed by growth of quartz in open spaces created by hydrofracturing, the characteristic feature being mostly euhedral cores dusted by tiny hematite flakes. In one occurrence there are also frondlike aggregates and possible earlier cavity linings of hematite, overgrown by quartz, that potentially formed by maturation of ferruginous gels first deposited in the openings. The trace element geochemistry of the jasperoids, apart from minor enrichment in uranium, provides no indication that they represent subsurface conduits for fluids that deposit Fe-Mn-Si at the seafloor, though this remains a possibility for some such deposits.
Resumo:
The Volga River discharge consists of the waters transferred by fast currents through channels and the waters which are passing through the shallow areas of the delta overgrown by cane. Using the hydrochemical data, it is possible to track distribution of the waters modified by 'biofilters' of macrophytes in the delta shallows starting from the external edge of the delta. The main distinctive features of these waters are the high content of dissolved oxygen, the abnormally high values of the pH, and the low content of dissolved inorganic carbon (both total and as CO2). These waters extend in the shape of 1 to 3-km-wide strips at a distance of 20-40 km from the outer border of the delta. The analysis of the data obtained during the expeditions run by the Institute of Oceanology of the Russian Academy of Sciences in 2003-2009, along with archived and published data, show that such 'modified' waters occur almost constantly along the outer edge of the Volga River delta.
Resumo:
Calcareous nannofossils were examined from the 400 cores recovered at 12 sites during Ocean Drilling Program Leg 108 in the eastern equatorial Atlantic Ocean and along the northwest African margin, representing a transect spanning 24° of latitude. Thirty calcareous nannofossil biohorizons were recognized in the Neogene and Quaternary sequences; only Site 661, located in water depths of 3500 m, contains a fossiliferous record older than the Oligocene. At Site 661, a 200-m-thick sequence of Upper Cretaceous sediments yielded Maestrichtian and uppermost Campanian nannofossils, yet a continuous Cretaceous/Tertiary boundary was not recovered. Widespread sediment slumps and turbidites deposited at many sites interrupted the pelagic sedimentation. A careful study of calcareous nannofossil and foraminifer assemblages correlated to paleomagnetic records suggests that "slumped" units at most sites were added as extra sediments to rapidly deposited pelagic sediments, with minor disturbance of the surrounding layers. Nannofossils are generally common to abundant and moderately preserved at all sites except for those located in two upwelling areas, where placoliths are etched and discoasters overgrown. Typical low-latitudinal zonal markers were used during this study, yet some of them were considered to be of little biostratigraphic value because of their inconsistent stratigraphic ranges and low abundances. This is especially apparent for the intervals representing the Miocene/Pliocene and Oligocene/Miocene boundaries. Characteristic nannofossils of cool-water conditions and low discoaster abundances occur at the coastal African upwelling and along the south equatorial divergence sites, signifying a stronger advection of cold waters toward the equator within the Canary and Benguela eastern boundary currents.